The BeagleBoard: $149 Linux System

The beagleboard is low cost fanless development board with Linux support.
And it is low cost, you can get one for $149 from digikey.
And it is low power, it uses less than 2 Watts and can run via USB power (although it does have a secondary power input).

So what do you get for $149? A bunch:

600 MHz superscalar ARM Cortex A8 processor

HD Video (720p) capable C64x DSP core

128MB Ram

256MB Flash

I2C, I2S, SPI, MMC/SD (via expansion connector)

DVI-D

JTAG

S-Video

SD/MMC+

Stereo Out

Stereo In

USB 2.0 HS OTG

RS-232 Serial

What kind of performance do you get? A lot:

1200 Dhrystone MIPS

10 Million Polygons/sec

OpenGL 1.1 and 2.0 support

What can you do with it? How about this:

That's the beagle board running Linux and an X server!
The hook-up is:

The beagleboard was designed by
some TI employees (it uses TI's
OMAP3530 processor).
However, the beagleboard is not built or sold by TI.
It's built by a contract manufacturer and available exclusively
from digikey.

The beagleboard is pretty open, the fact that it runs Linux tells you a lot.
In addition, according to Jason Kridner, one of the TI developers,
the schematics and layout are also available although I haven't yet located
them on the website.
TI provides a free compiler
for non-commercial use for the DSP.
If you're gonna do any serious development you'll need a hardware debugging
"dongle" to connect to the JTAG port, check out the
flyswatter,
its a mere $49 and it uses the OpenOCD software.
Check out the digikey beagleboard page
for links to other needed goodies.

One of the first things you notice as you examine the beagleboard is that
there's no ethernet and no wireless.
I asked Jason about this and his response was that during early development
the list of desired hardware additions grew to the
point where the only reasonable solution was to deny them all, if it could be
reasonably not be added to the board it wouldn't be.
Essentially, this meant that if there was a reasonable USB solution then it wouldn't go onboard.
The second thing you may notice is that you can't find the processor,
the RAM or the Flash chip. The reason for that is that they are all squeezed
on top of each other using a packaging technology called
POP (Package On Package).
So the chip in the center of the board that you would think ought to be the processor,
is the processor, along with the RAM and Flash.

There's a growing community of developers out there.
Check out beagleboard.org for more
information.

No ethernet on board, but what about USB? Can a USB hub be connected to this and a few USB ethernet adapters added?

The fact that the article mentions what was kept off the board, but doesn't mention 'but hey... you can just hook up a USB ethernet device and away you go..' really makes me wonder if there is any solution for ethernet at all.

The link to the design files is off the "Top Resources" page at http://beagleboard.org/hardware/design. Be aware that 0.4mm ball-pitch ball-grid array devices aren't for garage shops. There is a 0.65mm ball-pitch device option as well, which has some special features that allow use of design rules for 0.8mm ball-pitch design with minimal routing layers. While not quite for assembly with your toaster oven, it is quite a bit easier for the average board shop to handle.